Add RenderState.SetDepthFadeFalloff

src/common/rendering/hwrenderer/data/hw_renderstate.h

@@ -193,6 +193,7 @@ public:
 		mSurfaceUniforms.uLightFactor = 0.0f;
 		mSurfaceUniforms.uFogDensity = 0.0f;
 		mSurfaceUniforms.uLightLevel = -1.0f;
+		mSurfaceUniforms.uDepthFadeFalloff = 0.0f;
 		mSpecialEffect = EFF_NONE;
 		mLightIndex = -1;
 		mBoneIndexBase = -1;
@@ -263,6 +264,11 @@ public:
 		mSurfaceUniforms.uDesaturationFactor = 0.0f;
 	}
 
+	void SetDepthFadeFalloff(float falloff)
+	{
+		mSurfaceUniforms.uDepthFadeFalloff = falloff;
+	}
+
 	void SetTextureClamp(bool on)
 	{
 		if (on) mTextureClamp = TM_CLAMPY;

src/common/rendering/hwrenderer/data/hw_surfaceuniforms.h

@@ -44,6 +44,6 @@ struct SurfaceUniforms
 
 	float uAlphaThreshold;
 	int uTextureIndex;
-	float padding2;
+	float uDepthFadeFalloff;
 	float padding3;
 };

src/common/rendering/vulkan/shaders/vk_shader.cpp

@@ -185,6 +185,8 @@ std::unique_ptr<VulkanShader> VkShaderManager::LoadFragShader(FString shadername
 	if (!key.AlphaTest) definesBlock << "#define NO_ALPHATEST\n";
 	if (key.GBufferPass) definesBlock << "#define GBUFFER_PASS\n";
 
+	if (key.DepthFadeFalloff) definesBlock << "#define USE_DEPTHFADEFALLOFF\n";
+
 	if (key.Simple2D) definesBlock << "#define SIMPLE2D\n";
 	if (key.ClampY) definesBlock << "#define TEXF_ClampY\n";
 	if (key.Brightmap) definesBlock << "#define TEXF_Brightmap\n";

src/common/rendering/vulkan/shaders/vk_shader.h

@@ -79,7 +79,8 @@ public:
 			uint64_t UseLevelMesh : 1;  // USE_LEVELMESH
 			uint64_t FogBalls : 1;      // FOGBALLS
 			uint64_t NoFragmentShader : 1;
-			uint64_t Unused : 42;
+			uint64_t DepthFadeFalloff : 1;
+			uint64_t Unused : 41;
 		};
 		uint64_t AsQWORD = 0;
 	};

src/common/rendering/vulkan/vk_renderstate.cpp

@@ -258,6 +258,8 @@ void VkRenderState::ApplyRenderPass(int dt)
 	pipelineKey.ShaderKey.Detailmap = (uTextureMode & TEXF_Detailmap) != 0;
 	pipelineKey.ShaderKey.Glowmap = (uTextureMode & TEXF_Glowmap) != 0;
 
+	pipelineKey.ShaderKey.DepthFadeFalloff = mSurfaceUniforms.uDepthFadeFalloff > 0.0f;
+
 	// The way GZDoom handles state is just plain insanity!
 	int fogset = 0;
 	if (mFogEnabled)

wadsrc/static/shaders/scene/binding_rsbuffers.glsl

@@ -68,7 +68,7 @@ struct SurfaceUniforms
 
 	float uAlphaThreshold;
 	int uTextureIndex;
-	float padding2;
+	float uDepthFadeFalloff;
 	float padding3;
 };
 

wadsrc/static/shaders/scene/frag_main.glsl

@@ -27,6 +27,11 @@ void main()
 	if (material.Base.a <= uAlphaThreshold) discard;
 #endif
 
+#ifdef USE_DEPTHFADEFALLOFF
+	// To do: add linear depth sampling here
+	// material.Base.a *= clamp((depth.r - pixelpos.w) / uDepthFadeFalloff, 0.0, 1.0);
+#endif
+
 	FragColor = ProcessLightMode(material);
 
 #ifdef DITHERTRANS

wadsrc/static/shaders/scene/layout_shared.glsl

@@ -69,6 +69,7 @@ layout(push_constant) uniform PushConstants
 #define uLightDist data[uDataIndex].uLightDist
 #define uAlphaThreshold data[uDataIndex].uAlphaThreshold
 #define uTextureIndex data[uDataIndex].uTextureIndex
+#define uDepthFadeFalloff data[uDataIndex].uDepthFadeFalloff
 
 #define VULKAN_COORDINATE_SYSTEM
 #define HAS_UNIFORM_VERTEX_DATA